Probability Distribution of Discrete Random Variables

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a characteristic of a discrete random variable?

  • It can assume a countable number of values. (correct)
  • It can assume values from a continuum of numbers.
  • It can assume an uncountable number of values.
  • It represents outcomes that are derived from deterministic processes.

Which of the following describes the probability distribution of a discrete random variable?

  • It defines probabilities that can be negative.
  • It lists probabilities for each possible outcome. (correct)
  • It assumes the sum of probabilities is less than 1.
  • It associates probabilities with continuous outcomes.

In a random experiment, what is the definition of a random variable?

  • A constant that describes the average outcome.
  • A variable that assumes numerical values based on random outcomes. (correct)
  • A predetermined value for each experiment.
  • A variable summarizing the deterministic outcome.

What would be considered a discrete random variable?

<p>The number of students in a classroom. (B)</p> Signup and view all the answers

What is true about the probabilities in a probability distribution for a discrete random variable?

<p>The sum of probabilities must equal 1. (C)</p> Signup and view all the answers

Which of the following is an example of a discrete random variable?

<p>The number of cars passing through a toll booth in an hour. (D)</p> Signup and view all the answers

What is a defining feature of a continuous random variable?

<p>It can assume values across intervals on the number line. (D)</p> Signup and view all the answers

What does p(x) represent in the context of a probability distribution for a discrete random variable?

<p>The probability associated with a specific outcome x. (C)</p> Signup and view all the answers

What is the probability of observing 0 new cases of West Nile Virus in New England in a month?

<p>0.135 (A)</p> Signup and view all the answers

What is the probability of observing exactly 2 new cases of West Nile Virus?

<p>0.27 (B)</p> Signup and view all the answers

If the rate of new cases is 2 per month, what is the formula for calculating the probability of observing X cases?

<p>P(X) = 2^X e^{-2} / X! (A)</p> Signup and view all the answers

As the number of observed cases increases, what generally happens to the probabilities of observing specific counts in a Poisson distribution?

<p>They decrease to zero. (C)</p> Signup and view all the answers

What is the Poisson distribution primarily used to describe?

<p>Discrete occurrences over an interval (C)</p> Signup and view all the answers

Which of the following is a characteristic of the Poisson distribution?

<p>Describes rare events with a low probability of success (A)</p> Signup and view all the answers

What does the symbol λ (lambda) represent in the Poisson distribution?

<p>The rate at which events occur (B)</p> Signup and view all the answers

Which of the following best describes the shape of a Poisson distribution curve when λ increases?

<p>It approaches a normal distribution shape (C)</p> Signup and view all the answers

What type of events does the Poisson distribution not effectively model?

<p>Frequent events with high probabilities (A)</p> Signup and view all the answers

In the Poisson formula, what does the term $e$ represent?

<p>The base of the natural logarithm (D)</p> Signup and view all the answers

What is the relationship between the mean (μ) and the variance (σ²) in a Poisson distribution?

<p>Mean and variance are equal (D)</p> Signup and view all the answers

How does the distribution of occurrences change as λ increases from low values to high values?

<p>It becomes symmetric and unimodal (A)</p> Signup and view all the answers

What is the formula for the variance of a discrete random variable x?

<p>$E[(x - u)^2]$ (A)</p> Signup and view all the answers

According to Chebyshev's Rule, what is the minimum probability that a random variable x falls within one standard deviation of the mean?

<p>0 (A)</p> Signup and view all the answers

What is the expected probability of obtaining heads when flipping a fair coin?

<p>0.5 (C)</p> Signup and view all the answers

In a binomial distribution, what condition must be satisfied regarding the trials?

<p>Each trial must have the same probability of success (D)</p> Signup and view all the answers

What is the probability of getting exactly one tail when tossing two coins?

<p>0.5 (A)</p> Signup and view all the answers

According to the Empirical Rule, what percentage of the data will fall within three standard deviations of the mean in a normal distribution?

<p>99.7% (B)</p> Signup and view all the answers

What characterization can be made about the outcomes in a binary experiment?

<p>There are only two possible outcomes for each trial (C)</p> Signup and view all the answers

If the probability of success in a trial is given as p, what is the probability of failure?

<p>1 - p (D)</p> Signup and view all the answers

What is the probability that none of the selected students suffer from math anxiety?

<p>0.16 (B)</p> Signup and view all the answers

How is the expected value of a discrete random variable calculated?

<p>E(x) = Σ x P(x) (A)</p> Signup and view all the answers

Which of the following represents the variance of a discrete random variable?

<p>σ² = Σ (x - μ)² P(x) (C)</p> Signup and view all the answers

If two students are selected, what is the cumulative probability that at least one of them suffers from math anxiety?

<p>0.84 (A)</p> Signup and view all the answers

What does the standard deviation of a discrete random variable represent?

<p>The variability of the variable around the mean (A)</p> Signup and view all the answers

In the context of the provided data, which of the following statements is true?

<p>P(x=1) is equal to the sum of probabilities for P(NM) and P(MN). (C)</p> Signup and view all the answers

What is the formula to calculate the expected value (E(x)) for a discrete random variable?

<p>E(x) = Σ x P(x) (A)</p> Signup and view all the answers

Which event describes the situation where a selected student does not suffer from math anxiety?

<p>Event N (A)</p> Signup and view all the answers

What is the probability of seeing 5 striped trout in the next 100 yards, given an average of 3 striped trout per 100 yards?

<p>0.1008 (B)</p> Signup and view all the answers

Which of the following is the correct formula to calculate the probability of observing x occurrences in a Poisson distribution?

<p>P(x) = rac{e^{- u} u^x}{x!} (C)</p> Signup and view all the answers

If the average number of striped trout is increased to 5 per 100 yards, what would be the new probability of seeing exactly 5 striped trout?

<p>0.2079 (A)</p> Signup and view all the answers

In a discrete random variable table, which variable is typically represented in the rows?

<p>The random variable outcomes (C)</p> Signup and view all the answers

What is the value of P(X=0) for an average of 3 striped trout per 100 yards?

<p>0.6065 (C)</p> Signup and view all the answers

Which option does NOT accurately reflect an essential property of discrete random variables?

<p>They can represent continuous outcomes. (D)</p> Signup and view all the answers

Identifying the correct distribution type for modeling the number of striped trout in 100 yards, which statement is true?

<p>It is modeled by a Poisson distribution. (A)</p> Signup and view all the answers

For what value of $x$ does the Poisson distribution become negligible when the average rate is set to 3?

<p>Greater than 10 (D)</p> Signup and view all the answers

Flashcards

Random Experiment

An experiment where the result is not predetermined, and the outcome is uncertain.

Random Variable

A variable that takes on numerical values based on the outcomes of a random experiment.

Discrete Random Variable

A variable that can take on a finite number of values or a countably infinite number of values.

Continuous Random Variable

A variable that can take on any value within a given range.

Signup and view all the flashcards

Probability Distribution for Discrete Random Variable

A table or graph that shows the probability of each possible outcome of a discrete random variable.

Signup and view all the flashcards

Binomial Distribution

A discrete random variable where the probability of success in each trial is constant and trials are independent.

Signup and view all the flashcards

Poisson Distribution

A discrete random variable that represents the number of events occurring in a fixed period of time or place when events are independent and occur at a constant average rate.

Signup and view all the flashcards

Properties of Probability Distributions

The probability of a specific outcome of a discrete random variable must be between 0 and 1 (inclusive), and the sum of all probabilities for all possible outcomes must equal 1.

Signup and view all the flashcards

What is a random variable?

A random variable is a variable whose value is a numerical outcome of a random phenomenon.

Signup and view all the flashcards

What is a discrete random variable?

A discrete random variable is one whose value can only take on specific, distinct values.

Signup and view all the flashcards

What is a probability distribution?

A probability distribution lists all possible values of a discrete random variable and their corresponding probabilities.

Signup and view all the flashcards

What is expected value?

The expected value is the average value you would expect to obtain if you repeated an experiment many times.

Signup and view all the flashcards

What is variance?

The variance measures the spread of the probability distribution, or how far the values are, on average, from the mean.

Signup and view all the flashcards

What is standard deviation?

The standard deviation is the square root of the variance.

Signup and view all the flashcards

What is probability?

The probability of an event is the likelihood that the event will occur.

Signup and view all the flashcards

How is the mean of a discrete variable calculated?

The mean of a discrete variable is calculated as the sum of each value multiplied by its probability.

Signup and view all the flashcards

What is a random variable in a Poisson distribution?

The number of events occurring in a fixed period of time or place when events are independent and occur at a constant average rate.

Signup and view all the flashcards

Important Properties of Probability Distributions

The probability of each possible outcome must be between 0 and 1, and the sum of all probabilities for all possible outcomes must equal 1.

Signup and view all the flashcards

What are the key assumptions of a Poisson distribution?

Events occurring independently at a constant average rate.

Signup and view all the flashcards

What is the Poisson Distribution?

The Poisson Distribution describes the probability of a specific number of events occurring within a fixed interval of time or space, given that these events happen independently and at a constant rate.

Signup and view all the flashcards

What is lambda (λ) in the Poisson Distribution?

The average number of events that occur within the specified interval.

Signup and view all the flashcards

What is the formula for the Poisson Probability?

The formula calculates the probability of getting 'x' events in the defined interval, where λ is the average rate, 'e' is Euler's number (approximately 2.71828), and 'x!' represents the factorial of 'x'.

Signup and view all the flashcards

What are some examples of how the Poisson Distribution is used?

The Poisson Distribution is relevant when dealing with independent events occurring at a constant average rate, such as the number of customers arriving at a store, the number of defects in a manufacturing process, the number of meteorites hitting Earth, and many others.

Signup and view all the flashcards

What is the relationship between the mean and variance in the Poisson Distribution?

The average number of events per unit or interval, represented by λ, is also the variance of the Poisson Distribution.

Signup and view all the flashcards

How does the shape of the Poisson Distribution change with λ?

The shape of the Poisson Distribution's probability graph depends on λ. As λ increases, the distribution becomes more symmetrical.

Signup and view all the flashcards

What does the Poisson Distribution assume about the independence of events?

The Poisson Distribution assumes events are independent, meaning the occurrence of one event doesn't affect the probability of another event.

Signup and view all the flashcards

What is the significance of the Poisson Distribution?

The Poisson Distribution is a useful tool for modeling and analyzing rare events happening randomly over time or space.

Signup and view all the flashcards

Standard Deviation of a Discrete Random Variable

The standard deviation of a discrete random variable is a measure of its spread or variability. It is calculated as the square root of the variance, which measures how far, on average, the values of the variable deviate from its mean.

Signup and view all the flashcards

Expected Value of a Discrete Random Variable

The expected value (E(X)) of a discrete random variable X is the average of all possible values of X, weighted by their respective probabilities. It represents the long-run average value of the variable.

Signup and view all the flashcards

Variance of a Discrete Random Variable

The variance (Var(X)) of a discrete random variable X is a measure of its spread or variability. It is calculated as the average squared deviation of the values of X from its mean.

Signup and view all the flashcards

Chebyshev's Rule

Chebyshev's rule states that for any discrete random variable, at least 1 - 1/k^2 of the data values will fall within k standard deviations of the mean, where k is any number greater than 1.

Signup and view all the flashcards

Empirical Rule

The empirical rule is a statistical rule that applies to data that follows a normal distribution. It states that approximately 68% of the data falls within one standard deviation of the mean, 95% falls within two standard deviations, and nearly 100% falls within three standard deviations.

Signup and view all the flashcards

Bernoulli Trial

A Bernoulli trial is a random experiment with only two possible outcomes: success or failure. The probability of success (p) is constant and the trials are independent.

Signup and view all the flashcards

Binomial Experiment

A binomial experiment is a sequence of Bernoulli trials with a fixed number of trials, where each trial is independent and has the same probability of success.

Signup and view all the flashcards

Binomial Random Variable

A binomial random variable is a discrete variable that counts the number of successes in a fixed number of Bernoulli trials.

Signup and view all the flashcards

Lambda (λ) in Poisson Distribution

The average number of events expected to occur in a given time period or place.

Signup and view all the flashcards

P(x) in Poisson Distribution

The probability of observing exactly x events within the given time period or place.

Signup and view all the flashcards

P(x or more) in Poisson Distribution

The probability of observing at least x events within the given time period or place.

Signup and view all the flashcards

P(x or less) in Poisson Distribution

The probability of observing fewer than x events within the given time period or place.

Signup and view all the flashcards

P(x) in Binomial Distribution

The probability of getting exactly x successes in n trials (n ≥ x ), with probability of success p in each trial.

Signup and view all the flashcards

P(x or more) in Binomial Distribution

The probability of getting at least x successes in n trials.

Signup and view all the flashcards

Related Documents

More Like This

Use Quizgecko on...
Browser
Browser